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<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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<body>

</body>
<script>
  "use strict"; {
    void 0 === undefined          // true
    void 1 === undefined          // true
    void {} === undefined         // true
    void 'hello' === undefined    // true
    void void 0 === undefined     // true
    // void总是返回undefined
  };
</script>

</html>